Microfabrication system based on two-photon lithography

需要一种设备，将使三维（3D）结构的制造降低到亚微米结构尺寸。微加工系统应该允许制造最广泛的3D几何形状，特别是具有高纵横比的结构，凹痕，具有复杂拓扑的结构以及不能被描述为平面投影的结构。该系统应该能够将体积结构缩小到一立方厘米的量级。需要多尺度能力，即根据所需的结构尺寸使用不同的结构模式，因此粗结构可以比细结构更快地生产。通过这种方式，将有可能以适度的时间支出构建甚至相对较大的卷。其他重要的要求是所使用材料的生物相容性和低表面粗糙度，例如在光学应用中发挥作用。微加工系统最重要的应用领域之一将是微流体。例如，在相应的项目中，将需要微流体供应网络、芯片实验室系统结构或光流体元件。对市场上现有器件的研究表明，总的来说，只有基于双光子光刻（2PL）的系统才能满足这些要求。这里，在紫外光下聚合的光聚合物溶液作为起始材料。选择辐照光的波长，使两个光子的吸收是引发聚合所必需的。因此，聚合过程非线性地依赖于光强。结果，在激光聚焦中获得了一个非常小的空间区域，该区域的强度足以引发聚合。这使得制造尺寸在亚微米范围内的非常精细的结构成为可能。在实际实施中，激光束扫描光聚合物溶液，该溶液在此过程中局部硬化。然后可以除去未聚合的溶液，使激光束扫描的体积最终形成3D结构。

A device is requested that will enable the fabrication of three-dimensional (3D) structures down to submicron structure sizes. The microfabrication system should allow the fabrication of the broadest possible class of 3D geometries, particularly structures with high aspect ratios, undercuts, structures with complex topologies, and structures that cannot be described as a projection onto a plane. The system should be able to structure volumes down to the order of one cubic centimeter. Multiscale capability is desired, i.e. different structuring modes are to be used depending on the desired structure size, whereby coarse structures can be produced faster than fine ones. In this way, it will be possible to structure even relatively large volumes with moderate time expenditure. Other important requirements are the biocompatibility of the materials used and low surface roughness, which comes into play for applications in optics, for example. One of the most important areas of application for the microfabrication system will be in microfluidics. In the corresponding projects, microfluidic supply networks, structures for lab-on-a-chip systems or optofluidic components will be required, for example. Research into the devices available on the market has shown that, on the whole, these requirements are only met by systems based on two-photon lithography (2PL). Here, a solution of photopolymers that polymerize under UV light serves as the starting material. The wavelength of the irradiated light is chosen such that the absorption of two photons is necessary to initiate polymerization. Thus, the polymerization process depends nonlinearly on the light intensity. As a result, a very small spatial region is obtained in the laser focus where the intensity is sufficient to initiate polymerization. This results in the possibility to fabricate very fine structures with sizes in the submicrometer range. In practical implementation, a laser beam scans the photopolymer solution, which hardens locally in the process. The non-polymerized solution can then be removed so that the volumes scanned by the laser beam finally form the 3D structure.